The present invention relates broadly to manual rack and pinion jacks used in conjunction with recreational boat trailers. More particularly, the present invention relates to a rack and pinion jack having a safety quick-release mechanism which facilitates quick and convenient lowering or raising of the jack during use. Moreover, the present invention relates to a safety quick-release gear assembly adapted to be retro-fitted to an existing rack and pinion jack. The invention is believed best classified in U.S. utility class 254, subclass 97.
It has long been known to employ rack and pinion mechanisms in jacks. Typical jacks comprise a stanchion adapted to contact a supporting surface and a stanchion-control housing coupled to the trailer tongue or bumper of the vehicle to be elevated. Such jacks generally comprise a lever or crank which engages an internal gear for vertically moving the stanchion relative to the housing. This in turn elevates or lowers the trailer tongue relative to the tow vehicle. Representative prior art rack and pinion jacks are described by Ketel, U.S. Pat. No. 2,233,135, issued Feb. 25, 1941 and in U.S. Pat. No. 3,466,011, issued to Hewes et al. on Sept. 9, 1969. It is also known in the prior art to provide some form of safety latching mechanism to prevent accidental disengagement of the gear assembly from the rack, which might cause an unexpected and dangerous drop of the trailer.
As will be appreciated by sportsman and hobbyists familiar with the use of typical prior art jacks, a jack may be raised or lowered several times during a particular outing. Trailer jacks typically used with recreational boats are normally semi-permanently mounted upon the boat trailer tongue and must be raised above ground level for transport. They must be lowered again when it is desired to detach the trailer. Typically, before the trailer is disconnected from the tow vehicle, the jack stanchion will be lowered so that its base firmly contacts the ground, whereby to maintain the trailer tongue elevated for subsequent connection or disconnection. Thus the user is not required to exert extreme effort to lift the full weight of the trailer into alignment with the hitch. When the jack must be used with various vehicles of different sizes, it also may be necessary to crank the jack up or down to align the trailer tongue with the vehicle.
Thus, one major disadvantage encountered with the use of prior art jacks known to me is that the user must manually crank the jack up or down, and the user is not able to selectively disengage the gears to quickly raise or lower the jack when desired. Thus lowering the trailer or vehicle after service involves substantial expenditure of additional effort and time. Manual cranking required to raise or lower the tongue of the trailer to the necessary height to accommodate different vehicles has also proven to be too time-consuming and vexatious.
To overcome this disadvantage, various means for selectively disengaging the gear from the rack have been suggested in the prior art. Of particular relevance to the present invention is Weber et al., U.S. Pat. No. 3,934,852, issued Jan. 27, 1976. The jack described therein includes a worm gear releasably latched in position upon a rack and operatively retained by a tiltable hand crank. When the safety latch is deployed, the user must crank the jack to effectuate lowering or raising of the trailer. To freely slide the jack up or down without cranking, the user must manually depress the latch and simultaneously tilt the crank handle inward to release the gear from the rack. The main advantage of the prior art structure is that it greatly reduces the risk of inadvertent disengagement of the gear, since the user must give considerable attention and effort to release the safety latch.
However, it is my experience that the release mechanism of the Weber '852 reference is extremely cumbersome and inconvenient to use. Moreover, use of the referenced prior art device involves substantial risk of injury to the user, since the release latch is positioned proximate the crank handle where the user's hand may be impacted by the handle when it is released or wedged between the crank handle and the gear housing. Additionally, it is difficult for the unskilled user to readily visually discern whether the safety latch has been released or is still engaged. The user would not be able to readily detect and promptly replace or repair a weakened or defective spring in this prior art device, unexpected accidental release could easily occur. Hence it would be desirable to provide an improved quick-release mechanism for a safety jack which may be safely and conveniently deployed by a user and which is readily monitored in use.
Because a trailer jack is typically a rather costly item, a purchaser would likely be dissuaded from replacing a relatively good jack in the interest of enhanced safety. Moreover, it is unlikely that a user would go to the trouble and expense of replacing an otherwise sturdy, usable jack due to simple failure of the safety latch mechanism. In the prior art known to me, no means are suggested for conveniently replacing a worn or outdated jack gear mechanism or adding safety devices to existing jacks. It would thus seem desirable to provide a jack gear safety mechanism which could be conveniently retrofitted to an existing jack stand.